We are faced with a real puzzle, we can`t find the defect on the faulty station, really not!
The defective station is functioning perfectly well since it is back in Switzerland.
Of course, what did you really expect? The HS 'always works fine'. Aside from a random pass element/switch (the part that actually turns the heater on and off) failure is almost certainly tied up in some subtle software issue. Serious simulations may be the only way to tie it down. It could also be power related, even RFI (Radio Frequency Interference) unique to the the owner's condition. Murphy will insist that it be obscure, as is his nature, if he gets a chance. Beta testing is done to uncover just this sort of stuff, solution comes usually from 'Root Cause Analysis'. That it nailing the exact problem down.
The best solution may be in software/hardware protection. The vape needs to 'fail safe'. For instance a hardware fix that times out on applying heat in a second or two unless reset by the processor. If it turns the heater on, does some housekeeping, monitors the temperature rise, then shuts the heat down when the magic level (or time) is reached you're open to the processor 'hanging up' and leaving the fire on.
As we used to say in similar situations, "If it was easy, we'd have the janitor do it".........
IMO the product is sound and very useful, there's just a gremlin lurking in there somewhere. Not to offend the unknown consultant but this might not be a job for an Academic. It's not the sort of experience they usually have. IMO you need some serious 'design review' to go with the failure analysis. Not a common skill set.
I hope you keep after it, the goal is worth having I think. As they say, 'the risks are high, but so are the rewards'.
Best wishes, we're in this too.
OF
Edit: I should also have mentioned this is not unique to the HS, there's a single report of a Summit run away. The fellow 'shut it off' and put it in his pants pocket and went inside the PO (?) to feel the heat and find 'vapor pouring out the vents'.
As we push for shorter and shorter times we need more an more power that can cause serious problems if it 'gets off the leash'. Having the throttle stick on your new Lexis is a lot more exciting than on a '73 VW bug.......
OF